1. Field of the Invention
The present invention relates to an anti-reflection coating composition which is useful for minute processing in the lithography process employing various kinds of radiation, and is especially preferred for the production of integrated circuit chips.
2. Description of the Prior Art
In the manufacturing processes of integrated circuit chips, in order to obtain higher integration, there has been progress in making the processing size to be minute in the lithography process. In the lithography process, a resist composition solution is applied on a substrate, and the masking pattern is transcribed by a reduction projection exposure system (stepper), and it is developed with an appropriate developer to obtain a desired pattern. However, the substrate with high reflectivity used in this process such as aluminum, aluminum-silicon alloy and aluminum-silicon-copper alloy, polysilicon, and tungsten silicide reflects radiation on the surface. There has been the problem that halation occurs in the resist pattern due to this influence and that a minute resist pattern cannot be reproduced precisely.
In order to overcome this problem, it is proposed to install an anti-reflection coating which has a nature of absorbing radiation reflected from the substrate under the resist film to be formed on the substrate. As such an anti-reflection coating, known are inorganic coatings such as titanium coating, titanium dioxide coating, titanium nitride coating, chromium oxide coating, carbon coating, and α-silicon coating formed by methods such as vacuum coating, CVD, and sputtering. However, because these inorganic anti-reflection coatings have conductivity, there has been the shortcoming that they can not be used for manufacturing integrated circuits and requires special apparatuses, such as a vacuum evaporator, a CVD apparatus, and a sputtering apparatus for forming an anti-reflection coating. In order to overcome the shortcoming of inorganic anti-reflection coating, in Japanese Laid-open publication (Kokai) No. 59-93448 Public Report proposed is an organic anti-reflection coating made of polyamic acid (co)polymer or polysulfone (co)polymer and a dye. Because the anti-reflection coating has no electric conductivity and the composition constituting this anti-reflection coating dissolves in an appropriate solvent, it can be applied onto a substrate in the form of solution without any special device as in the case of the formation of a photoresist film.